Design and testing of a kinematic package supporting a 32×32 array of GaAs MQW modulators flip-chip bonded to a CMOS chip

Innovative approaches to the design and packaging of a high-performance module supporting a 32×32 array of GaAs multiple quantum-well (MQW) modulators flip-chip bonded to a 9×9 mm² complementary metal-oxide-semiconductor (CMOS) chip are described. The module integrates a minilens array, a copper heat spreader, a thermoelectric cooler (TEC) and an aluminum heatsink. The minilens array is aligned and packaged with the chip using a novel six degrees of freedom (DOFs) alignment technique. The kinematic design allows for the manual insertion of the module into a free-space optical system with no need for further adjustments. The chip is mounted directly on a flexible printed circuit board (PCB) using a chip-on-board approach, providing over 200 bond pad connections to the chip. Impedance-controlled lines were operated at 1.0 Gb/s with a crosstalk of 4.0% between nearest neighbor lines. The junction-to-TEC thermal resistance is 0.4°C/W, allowing for the use of a single-stage TEC to regulate the chip at an operating temperature of 40°C under a maximum thermal load of 13.1 W